This invention relates to a plate making apparatus using a plate material having flexibility. In addition, this invention relates to a printing method, a printing apparatus, and a packing sheet material for a printing plate material according to a planographic printing technique. Further, this invention relates to a plate material placement method and a plate material placement apparatus for placing a plate material on a plate cylinder of a printing apparatus or a plate making apparatus.
In a planographic printing printing apparatus, generally a printing plate is wrapped around a plate cylinder and is fixed mechanically and printing is executed in this state.
However, a planographic printing plate with an easy-to-handle material other than metal (for example, plastic film, paper, etc.,) as a support has a drawback in dimension stability. For example, the plate warps partially by the friction between a blanket cylinder and the plate during printing and print dimensions and print position accuracy relative to paper are impaired.
Therefore, hitherto the plate using a support material as described above has been limited to simple use for printing a small number of sheets not much requiring register accuracy of printed matter and has not been used for high-grade printing of multicolor and elaborate printing or full-scale printing using a large printing apparatus.
To solve such a problem, Japanese Utility Model Unexamined Publication No. Sho. 58-1046 (JP-A-58-1046U) proposes a method of bonding a plate material directly to a plate cylinder or a preparatory form plate using an acrylic or rubber both-sided adhesive sheet or spray adhesive, for example.
However, in such a method, the printing plate is strongly bonded to the plate cylinder, thus a new problem occurs, namely, the position of the printing plate on the plate cylinder cannot be finely adjusted or workability of discharging the plate after print, etc., worsens extremely.
On the other hand, plate making and print method by CTP (computer to plate) finding spreading use in recent years have advantages that dimension, position accuracy of an image (exposure) relative to a plate material is good and that registration in multicolor printing is easy as compared with conventional plate making and printing method (exposure step of plate material is contact exposure using a lith type film).
However, the planographic printing plate having the support made of a plastic film, paper, etc., as described above involves the problems as described above, thus the advantage that registration in multicolor printing is easy in the CTP is not used fully.
On the other hand, hitherto, various techniques for placing a plate material on a plate cylinder of a printing apparatus, etc., have been known. FIGS. 23 and 24 show a printing plate placement apparatus 260 for placing a plate material on a plate cylinder of a printing apparatus. FIG. 24 is an X arrow view in FIG. 23 and FIG. 23 is a sectional view taken on line Yxe2x80x94Y in FIG. 24.
As shown in FIG. 23, a plate cylinder 261 of a printing apparatus has a shape such that a part of a column is cut in an axial direction of the column and that a groove part 265 is made in a roughly flat plane of the cut end, which will be hereinafter referred to as flat face part 261a. Provided in the groove part 265 are a plate front clamp mechanism 262 for clamping the plate front of the front end of a printing plate 270 and a plate back clamp mechanism 263 for clamping the plate back of the rear end of the printing plate 270. The clamp mechanism 262 (263) comprises a lower tooth 262b (263b) with the top face forming roughly the same flat face as the flat face part 261a and an upper tooth 262a (263a) being supported on the lower tooth for rotation and capable of clamping the plate front between the upper tooth and the top face of the lower tooth.
Peak parts 261c are formed between the flat face part 261a of the plate cylinder 261 and a curved surface part 261b. With some plate cylinders, peak parts may be formed between the lower tooth top face of clamp mechanism in place of the flat face part and curved surface part although not shown Normally, the portion where the flat face part 261a and the curved surface part 261b cross each other is rounded as a curved surface having a radius of 10 to 20 mm, but such a portion will also be called peak part in the specification.
As shown in FIG. 24, the lower tooth 262b of the plate front clamp mechanism is formed on the top with two positioning pins 264 spaced from each other in an axial direction of the plate cylinder 261. Notches 266 are formed at the positions of the upper tooth 262a of the plate front clamp mechanism corresponding to the positioning pins 264. Notches 271 are also formed at the positions of a plate front 270a of the printing plate 270 indicated by phantom lines in the figure corresponding to the positioning pins 264.
By the way, needs for plate materials made of inexpensive and easy-to-handle material other than metal, such as plastic film or paper, which will be called flexible plate materials in the specification, have grown with recent small lots and versatility of print matter. However, since such plate materials are highly flexible, several problems occur when the plate material is placed on a plate cylinder.
For example, in the printing plate placement apparatus 260, when the operator inserts the plate front 270a of the flexible printing plate 270 shown in FIG. 24 between the upper tooth 262a and the lower tooth 262b of the plate front clamp mechanism while holding the plate back 270b of the printing plate 270 and abuts the plate front against the two positioning pins 264, the plate front 270a may become deformed and be fixed in this deformed state. That is, in a plate cylinder on which a printing plate of a royal octavo or larger can be placed, the spacing between two positioning pins 264 becomes considerably wide and at the printing plate placing time, if the operator over pushes the flexible printing plate 270 even a little, the printing plate 270 becomes deformed so that the plate front 270a projects in the push direction from between the two positioning pins 264. However, if the printing plate 270 is pushed insufficiently for avoiding such deformation, it cannot be positioned accurately.
As shown in FIG. 23, the flexible printing plate 270 is hard to be conformable to the outer peripheral surface of the plate cylinder 261 and tends to float up from the outer peripheral surface of the plate cylinder in the proximity of the peak part 261c formed between the flat face part 261a and the curved surface part 261b of the plate cylinder 261.
To prevent such floating of the printing plate 270, while strongly pulling the plate back of the printing plate whose plate front is clamped in the plate front clamp mechanism 262, the operator rotates the plate cylinder and places the printing plate 270 thereon. At this time, however, the pulled part of the plate back of the flexible printing plate 270 is extended.
As in the example, the placeability of a flexible plate material on a plate cylinder is poor and it is difficult to always place a flexible plate material on a plate cylinder in a constant state. Therefore, if the flexible plate material is applied to multicolor printing (for example, four-color printing), etc., requiring a number of plate cylinders and accurate registration among the plate cylinders, an out-of-registration phenomenon occurs.
Accordingly, the object of the present invention is to solve the above-mentioned problem.
It is an object of the invention to provide a plate making apparatus which uses a planographic printing plate comprising a plastic film, paper, etc., as a support and reliably holds a plate material on a plate cylinder and accurately positions the plate material on the plate cylinder, thereby enabling multicolor planographic printing, and can use a roll-like plate material.
The object of the invention is accomplished by a plate making apparatus for forming an image on a flexible plate material made of a photosensitive material wound like a roll for making a plate, placing the made printing plate on a plate cylinder, and executing planographic printing in multiple colors, the plate making apparatus comprising a cutter being placed between a storage section of the plate material and an exposure section for cutting the roll-like plate material like a sheet and punch means for making plate cylinder engagement holes in the left and right margins of the plate material along the transport direction thereof, the plate cylinder engagement holes to be engaged in protrusions disposed in the circumferential direction of the left and right margins of the plate cylinder, the cutter and the punch means being formed in one piece.
The plate making apparatus of the invention cuts a roll-like plate material, makes plate cylinder engagement holes, and executes exposure at the same time or consecutively, so that the steps can be executed efficiently. Since exposure and printing are executed based on the same positioning reference holes, registration in multicolor printing is easy to perform.
In addition to this, it is also an object of the present invention to provide a printing method, a printing apparatus, and a packing sheet material for a printing plate material wherein a planographic printing plate comprising a plastic film, paper, etc., as a support is used, wherein the plate does not warp partially at the printing time and print position accuracy relative to the print dimensions and paper is not impaired, wherein registration in multicolor printing is easy in plate making and print method by CTP, and wherein worsening of workability at the printing time, the problem in the related art, can be solved.
The object of the invention is accomplished by the following:
(1) A printing apparatus using a flexible plate material for executing planographic printing, wherein the surface roughness of a plate cylinder on which the plate material is placed is formed as a coarse face with center line average roughness Ra ranging from 3 xcexcm to 12 xcexcm.
(2) A printing method using a flexible plate material for executing planographic printing, wherein printing is executed using a substance wherein the surface roughness of at least either of a surface of a plate cylinder on which the plate material is placed and a rear face of the plate material is formed as a coarse face with center line average roughness Ra ranging from 3 xcexcm to 12 xcexcm.
(3) A packing sheet material for a planographic printing plate material comprising a sheet-like base substance wherein the surface roughness of at least one face of the base substance is formed as a coarse face with center line average roughness Ra ranging from 3 xcexcm to 12 xcexcm.
(4) A printing method wherein the material in the above-mentioned item (3) is installed on a plate cylinder so that the coarse face side of the material is placed on the planographic printing plate material side.
Note that in the case where the surface roughness of the coarse face is equal to or more than 3 xcexcm, projected portions formed on the coarse face can be eaten into the plate material, to thereby obtain an effect suppressing a strain/warp (extension) of the plate material.
If the surface roughness of a coarse face is less than 3 xcexcm as center line average roughness Ra, a warp (extension) suppression effect of a plate material can be little expected and if the surface roughness is larger than 12 xcexcm as center line average roughness Ra, protrusions affect the surface of the plate material, causing an image defect to occur on print matter.
Furthermore, it is also an object of the present invention to provide a plate material placement method and a plate material placement apparatus which are capable of placing a flexible plate material on a plate cylinder reliably and easily and can also be realized by adding some improvement to an already installed printing apparatus, etc.
The object of the invention is accomplished by the following:
(1) A plate material placement method for placing a flexible plate material on a plate cylinder comprising a plate front clamp mechanism and a plate back clamp mechanism each having an upper tooth and a lower tooth, the method comprising the steps of:
inserting a plate front of the plate material between the upper tooth and the lower tooth of the plate front clamp mechanism and abutting the plate front against at least three positioning pins projected from the lower tooth for positioning and fixing the plate front;
providing a press roller;
winding the plate material around the plate cylinder while pressing the plate material against the outer peripheral surface of the plate cylinder by the press roller before and after at least a peak part of the outer peripheral surface of the plate cylinder; and
inserting a plate back of the plate material between the upper tooth and the lower tooth of the plate back clamp mechanism with the neighborhood of the plate back bent and fixing the plate back.
(2) A plate material placement method for placing a flexible plate material on a plate cylinder comprising a plate front clamp mechanism and a plate back clamp mechanism each having an upper tooth and a lower tooth, the method comprising the steps of:
attaching a pin abutment member having higher rigidity than the plate material to a positioning pin projected from the lower tooth and fixedly securing the plate front of the plate material to the pin abutment member at the same time as inserting the plate front of the plate material between the upper tooth and the lower tooth of the plate front clamp mechanism, thereby positioning and fixing the plate material;
providing a press roller;
winding the plate material around the plate cylinder while pressing the plate material against the outer peripheral surface of the plate cylinder by the press roller in adjacent to at least a peak part of the outer peripheral surface of the plate cylinder; and
inserting and fixing a plate back of the plate material between the upper tooth and the lower tooth of the plate back clamp mechanism while a portion of the plate material adjacent to the neighborhood of the plate back is being bent.
(3) A plate material placement method for placing a flexible plate material on a plate cylinder comprising a plate front clamp mechanism and a plate back clamp mechanism each having an upper tooth and a lower tooth, the method comprising the steps of:
fixedly securing a pin abutment member having higher rigidity than the plate material to a plate front of the plate material, inserting the plate front of the plate material between the upper tooth and the lower tooth of the plate front clamp mechanism, abutting the pin abutment member against a positioning pin projected from the lower tooth, and positioning and fixing the plate front;
providing a press roller;
winding the plate material around the plate cylinder while pressing the plate material against the outer peripheral surface of the plate cylinder by the press roller in adjacent to at least a peak part of the outer peripheral surface of the plate cylinder; and
inserting and fixing a plate back of the plate material between the upper tooth and the lower tooth of the plate back clamp mechanism while a portion of the plate material adjacent to the neighborhood of the plate back is being bent.
(4) A plate material placement apparatus for placing a flexible plate material on a plate cylinder comprising a plate front clamp mechanism and a plate back clamp mechanism each having an upper tooth and a lower tooth, the apparatus comprising:
a press roller for pressing the plate material against the outer peripheral surface of the plate cylinder in adjacent to at least a peak part of the outer peripheral surface of the plate cylinder, wherein
at least three positioning pins against which a plate front of the plate material is abutted for positioning the plate front are placed on the lower tooth of the plate front clamp mechanism in a predetermined spacing in an axial direction of the plate cylinder.
(5) A plate material placement apparatus for placing a flexible plate material on a plate cylinder comprising a plate front clamp mechanism and a plate back clamp mechanism each having an upper tooth and a lower tooth, the apparatus comprising:
a press roller for pressing the plate material against the outer peripheral surface of the plate cylinder in adjacent to at least a peak part of the outer peripheral surface of the plate cylinder; and
a pin abutment member having higher rigidity than the plate material, to which a plate front of the plate material is fixedly secured, for abutting a positioning pin placed on the lower tooth of the plate front clamp mechanism, thereby positioning the plate material.
(6) The plate material placement apparatus in the above-mentioned item (4) or (5) further including guide members for guiding the plate front of the plate material into the plate front clamp mechanism.
(7) The plate material placement apparatus in any one of the above-mentioned items (4) to (6) wherein the width of one of the positioning pins in the axial direction of the plate cylinder is formed wider than that of each of other positioning pins in the axial direction of the plate cylinder.
(8) The plate material placement apparatus in any one of the above-mentioned items (4) to (7) further including means for rotating the plate cylinder, means for detecting a rotation position of the plate cylinder, and means for stopping rotating the plate cylinder at a predetermined position when the plate material is placed.
(9) The plate material placement apparatus in any one of the above-mentioned items (4) to (8) wherein a packing sheet material comprising a sheet-like base substance with at least one face formed as a coarse face is wound around the plate cylinder so that the coarse face becomes the surface side.
(10) The plate material placement apparatus in any one of the above-mentioned items (4) to (8) wherein a packing sheet material comprising a sheet-like base substance with at least one face formed as an adhesive face is wound around the plate cylinder so that the adhesive face becomes the surface side.
According to (1) and (4), the plate front of the flexible plate material is abutted against the three or more positioning pins and is positioned, thus the spacing between the positioning pins becomes narrow and the plate material does not become deformed in such a manner that the plate front projects from between the positioning pins. When the plate material is wound around the plate cylinder, the press roller presses the plate material against the outer peripheral surface of the plate cylinder in the proximity of the peak part of the outer peripheral surface of the plate cylinder (peak part on the plate front clamp mechanism side and peak part on the plate back clamp mechanism side), so that the plate material does not float up from the outer peripheral surface of the plate cylinder. Therefore, the placement property of a flexible plate material on the plate cylinder improves remarkably and a load can be taken off the operator.
According to (2), (3), and (5), the plate front of the plate material is protected by the highly rigid pin abutment member for preventing the plate front from becoming deformed. Therefore, the number of the positioning pins need not be increased and the method or apparatus can be applied comparatively easily to already installed printing apparatuss and plate making apparatus. Metal, etc., can be selected as the material of the pin abutment member having higher rigidity than the plate material, but the material is not limited.
According to (6), when the plate material is set on the guide means, it is guided into the plate front clamp mechanism by the guide means. Therefore, insertion of the plate front of the plate material between the upper tooth and lower tooth of the plate front clamp mechanism is simplified.
According to (7), the plate material is formed with as many notches, etc., as the number of positioning pins, each notch, etc., whose inner peripheral surface engages one positioning pin having a wider width closely, whereby after the plate material is engaged in the wider positioning pin, it can be engaged in other positioning pins easily. Therefore, the placement property of a plate material can be enhanced without impairing the positioning accuracy of the plate material.
According to (8), the operator need not rotate or stop the plate cylinder at the plate material placing time. Therefore, a load can be furthermore taken off the operator and the plate material can be placed on the plate cylinder rapidly.
According to (9) and (10), the packing sheet material supports the plate material put thereon by a high frictional force or high adhesion. Therefore, the dimension stability of the plate material after the plate material is placed on the plate cylinder can be improved. When the plate material is placed on the plate cylinder, a shift of the plate material on the outer peripheral surface of the plate cylinder can be prevented reliably.
Japanese Patent Unexamined Publication No. Sho. 63-191636 (JP-A-63-191636) discloses a plate back insertion apparatus of a sheet printing apparatus comprising a roller for pressing a printing plate against the outer peripheral surface of a plate cylinder. However, the apparatus is intended for printing plates made of metal and does not consider a problem occurring when a flexible printing plate is mounted. For example, the gazette does not disclose technical idea for abutting the plate front of a printing plate against three or more positioning pins to suppress deformation of the plate front or fixedly securing a pin abutment member having higher rigidity than a printing plate and abutting the pin abutment member against a positioning pin or technical idea for pressing a printing plate against the outer peripheral surface of a plate cylinder by a roller in adjacent to the peak part of the outer peripheral surface of the plate cylinder.
Japanese Utility Model Unexamined Publication No. Hei. 6-71130 (JP-A-6-71130U) discloses a printing plate auto placement apparatus comprising a back push roller for pressing a flexible printing plate against a plate cylinder, but does not disclose the technical idea according to the invention described above either. The plate back clamp mechanism of the printing plate auto placement apparatus disclosed in the JP-A-6-71130U can pull the plate back with the plate back clamped.
In the invention, the press roller presses a plate material against the outer peripheral surface of the plate cylinder in adjacent to the peak part of the outer peripheral surface of the plate cylinder, so that the plate material is brought into intimate contact with the plate cylinder without pulling the plate back when the plate back clamp mechanism clamps the plate back. Therefore, the plate back clamp mechanism in the invention may or may not be able to pull the plate back.